1. Field of the Invention
The present invention relates to a mobile Internet protocol (IP) service, and more particularly, to a method and apparatus for managing a mobile IP using network address translation (NAT) in a mobile network.
2. Description of the Related Art
Generally, a mobile IP service allows a terminal, after being moved, to have the same IP address that it had before moving.
As shown in FIG. 1A, a mobile host is allocated a unique IP address by a home agent in a home network. As shown in FIG. 1B, when the mobile host moves to a foreign network, it can access the Internet without changing its unique IP address. Here, the mobile host cannot access the Internet using an IP address that is allocated in one network in another network (or foreign network). In this case, a foreign agent in the foreign network allocates the mobile host a temporary address referred to as a care-of address (COA), so that the mobile host can communicate with the foreign network. Accordingly, a conventional mobile IP service provides an Internet service for only when a single host (for example, a cellular phone or a notebook) moves.
In the meantime, passengers in an airplane, ship, or train may want to use the Internet while seated. Here, the seats form a network, which is referred to as a mobile network. In order to accomplish a mobile IP for each host connected to the mobile network, a home agent, a foreign agent, and a host are required. However, conventionally, since all hosts at the individual seats connected to the mobile network are allocated an IP address, the network is inefficient in using and managing IP addresses, and also some IP addresses are wasted.